It has been known to use an electrolysis process in aqueous solution systems in order to produce hydrogen, ozone, hydrogen peroxide and other oxygen compounds. In other applications it is known to use the electrolysis method or the oxygen overvoltage optionally produced during the electrolysis which makes it possible to treat aqueous solutions at a higher potential than would be required to produce the substances mentioned hereinbefore as an example in order to use oxidizing agents produced during the electrolysis for the treatment of waste water, in particular for the treatment of bacteria.
Recently diamond or diamond like carbon material has been used as material of an electrode (anode) for electrolysis used to carry out such oxidation of the aqueous solution, this diamond being applied as a coating to an electrode substrate of a metallic material. Diamond like carbon material is known to the man skilled in the art as DLC (diamond like carbon).
It is known from EP 1 468 965 B1 to apply a diamond powder to a metallic electrode substrate in order to produce a suitable electrode.
EP 0 994 074 A1 discloses a diamond electrode for electrolysis, comprising a base body which is coated with a diamond layer produced by CVD (chemical vapour deposition).
Regardless of the different type for producing a coating of the electrode substrate with polycrystalline diamond, the known electrodes have a structure in which the diamond coating is applied to a metallic electrode substrate.
The direct coating of the metallic electrode substrate with polycrystalline diamond material can result in defects in the coating during operation of the electrode used as an anode, which can lead to high local currents and a resulting thermal alternating load on the electrode. Caused by the very different coefficients of thermal expansion of diamond and metal, this can result in the formation of micro-cracks in the metal surface which leave the metal particularly exposed to the electrochemical processes taking place during electrolysis. The consequence of this is a further intensification of the formation of defects in the coating which can lead to complete destruction of the electrode so that a frequent exchange of the known diamond electrodes is necessary as a result of correspondingly reduced lifetime.